Early on in the presidential campaign, some pundits argued that Donald Trump's candidacy was just a fleeting effort that would leave little impact on the race, but could ultimately bring more attention and revenue to the Trump business empire.

But more than a year later, both of those ideas may be wrong. Trump's candidacy has turned out to be serious - and the effects on his businesses may not have been as positive as he hoped. Foursquare, a location-based app where users can "check in" to various businesses and restaurants, released interesting data on Thursday showing that foot traffic to Trump-branded businesses appears to have fallen significantly during the presidential campaign.

In the past, Foursquare and its sister app, Swarm, have figured out how certain businesses are performing by scouring their data on the foot traffic of more than 50 million users, which includes both "check-ins" at various businesses and location-based data for people who allow the app to access their location in the background. The company accurately predicted a big drop in Chipotle's sales following a food poisoning scandal earlier this year, and successfully forecast how many iPhones Apple would sell after the launch of its 6S. Now it is using the same approach to examine Trump's businesses.

Foursquare found that, since Donald Trump announced that he was running for president in June 2015, foot traffic to Trump-branded hotels, casinos and golf courses has dropped. "Since spring, it's fallen more," the company says. The Trump Organization did not immediately respond to requests for comment.

Trump's businesses failed to see the gains in foot traffic that they typically do during the summer of 2015, Foursquare says. Things appeared to get worse this spring, as voters in states around the country went to the primaries. Foot traffic at Trump properties was down 17 percent year-on-year in March, April and June, and down 14 percent year-on-year in July.

Donald Trump's statements about Muslims and Latinos have drawn widespread rebuke from politicians in both parties and many other national leaders.

But the companies that do business with Trump have generally remained silent in the face of those polarizing remarks, and so far there's little evidence...

The data obviously only represents people who use Foursquare and Swarm, which is a select group. The company says that it has normalized that data against figures from the U.S. census to remove age and gender bias, but that urban dwellers are still somewhat over-represented in their figures.

One likely reason for the fall in traffic, Foursquare says, is that Trump's hotels, casinos and golf courses are mainly located in "blue states," like New York, Hawaii, New Jersey and Illinois, and depend on local visitors from those regions. In blue states, Trump's properties have seen foot traffic decrease by more than the national average, for example falling 20 percent year-on-year in July 2016.

Foursquare's analysis also shows that this drop has been particularly driven by women, who tend to have more unfavorable opinions of Trump than men, polls show. Visits by women to Trump hotels, casinos and golf courses have fallen by nearly one-third this spring.